Atomic Structure Flashcards
Mass number
Atomic number
Isotope
Are atoms with the same number of protons but different number of neutrons
JJ Thompson
Plum pudding -
Atom consisted of positive “dough” with negative electrons
Ernest Rutherford
Gold foil experiment (Nuclear model of the atom) -
Shoot alpha particles at a gold foil to see if they go through or bounce back, as a result, he discovered the nucleus
Niels Bohr
Electrons orbiting -
He discovered that electrons orbit the nucleus at a fixed distance
James Chadwick
Neutron -
He discovered the neutron
Alpha particle
Contain two neutrons and two protons (helium atom)
Big, heavy, and slow-moving so therefore aren’t able to penetrate materials easily and stop quickly when traveling through the air
However, they are strongly ionising (when they collide with atoms to create ions)
Beta particles
They are electrons
Move quite fast and are small
Penetrate moderately and have a long-range in the air with their ionising ability being moderate
Gamma rays
They are very short-wavelength electromagnetic waves
Penetrate far into materials and pass straight through the air, therefore they are weakly ionising
They have no mass or charge
Radioactive
A substance containing unstable nuclei that becomes stable by emitting radiations
Background radiation
Radiation that is present at all times
E.g. food (bananas), x-rays, and cosmic rays from the Sun
Half-life
The time taken for the number of radioactive nuclei to halve
Carbon dating
Uses radioactive carbon to find the age of organic material
Uses of nuclear radiation
Medicine
X-rays
